1 A Novel Method to Facilitate Biodethatching Using Fungal Laccases: Optimization in a Field Study A Report to Georgia Green Environmental Foundation Mar 20, 2013 Sudeep Sidhu, Paul Raymer, Robert Carrow, Qingguo Huang Department of Crop & Soil Sciences, University of Georgia, Griffin ABSTRACT Organic matter buildup in the form of thatch or mat layers leads to several problems in turfgrass management systems. In a previous study, laccase enzyme solution proved effective in reducing the rate of accumulation of organic matter when applied at an activity level of 2.0 units cm -2 every two weeks for nine months on ‘Crenshaw’ creeping bentgrass (Agrostis stolonifera L.). A two year field experiment was conducted on creeping bentgrass to optimize the laccase activity level, frequency of application; to determine potential interactions with core aeration and topdressing cultural practices; and to compare enzyme sources. Laccase enzyme from white-rot fungi, Trametes versicolor, was applied at five activity levels 0, 0.5, 1.0, 2.0 and 4.0 units cm -2 applied every two weeks. Frequency of laccase application was tested using a laccase activity level of 2.0 units cm -2 applied at frequency of 2, 4, 8, or 12 weeks. The common cultural management practice of core aeration and sand topdressing was compared with and without laccase enzyme at an activity level of 2.0 units cm -2 applied once a month. Three sources of laccase enzyme were also compared when applied at a standard activity level of 2.0 units cm -2 every two weeks. Results indicated that laccase treatments were effective at rates as low as 0.5 units cm -2 applied every two weeks and as infrequent as once a month when applied at rate of 2.0 units cm -2 . Monthly applications of laccase further reduced organic matter accumulation when applied in combination with core aeration and sand topdressing. INTRODUCTION One of the major problems in management of recreational turfgrass sites, especially golf greens, is accumulation of organic matter in the form of tightly intermingled dead and living plant tissue between the soil and green turfgrass. This high organic matter layer, known as thatch, consists of stolons, rhizomes, roots, crown tissue, leaf sheaths, and blades (Engel, 1954; Roberts and Bredakis, 1960). Cultural practices like core aeration followed by sand topdressing may cause formation of a mat layer which is a thatch layer mixed with sand or soil with sand most common on golf greens (McCarty, 2005). Mat layers are more common on greens and physical conditions in a mat layer can vary depending upon whether the percent sand or percent